Thermomechanical Characterization of a Fast Curing Epoxy Resin for Simulation of Surface Waviness

The interaction of process parameters and material properties represents a major challenge for reproducible manufacture of high quality composite parts with polymer matrix. Major phenomena that have to be taken into account are thermal expansion, chemical shrinkage as well as process-dependent curing and mechanical properties that lead to residual stresses and geometrical deviations on different length scales. The analysis of these effects is even more challenging when considering fast curing resins. This contribution presents the development of a simulation approach dedicated to the prediction of surface waviness originating from liquid injection molding (LCM). A fast curing epoxy resin used in automotive industry was characterized in terms of curing kinetics and thermomechanical properties. A generic cure cycle was derived. A simulation approach is presented which aims at the numerical analysis of process-related parameters and their influence on surface waviness. In a first step, the influence of the resin thermomechanical behavior and the tool boundary condition on surface deformation is evaluated during cooling. The presented work provides a basis for a comprehensive understanding of the underlying effects and prospectively allows a linkage to internal residual stresses. (C) 2020 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 23rd International Conference on Material Forming.